Elsevier

Engineering Structures

Volume 245, 15 October 2021, 112862
Engineering Structures

Collapse of the spatial double-layer cylinder shell by experimental study

https://doi.org/10.1016/j.engstruct.2021.112862Get rights and content

Highlights

  • This paper investigates the characteristics and rules of the seismic damage of large span spatial structure during the Lushan earthquake and discusses the possible causes of such damage.

  • A shaking table test was conducted with a down-scaled model of a double-layer cylindrical shell structure to obtain the dynamic response of a structure by reasonably arranging the acceleration, velocity and displacement measuring points. The failure pattern and progressive collapse process of the structure under a severe earthquake were investigated. The buckling of members increased with the increment of ground motion, although this effect was not considered in the present code for seismic design for double-layer shell spatial structures.

  • The seismic damage in the test was mainly represented by overall buckling of the upper chord, web member and lower chord, which is the direct reason for the structural collapse during a severe earthquake.

  • The test results indicated that the change in surface curvature of the structure resulting from deformation during a severe earthquake transformed gravitational potential energy into kinetic energy and caused chord members to impact and fracture, thereby inducing progressive collapse of the structure.

Abstract

Large span spatial steel structures, such as gymnasiums, exhibition halls, airport terminals, or railway hubs, have developed rapidly over the last four decades. However, the mechanical properties of these structures under complex loads, particularly their seismic performance under severe earthquakes, are not sufficiently understood. During the 2013 M7.0 Lushan earthquake in China, some of the large span spatial structures suffered damage of varying degrees, which necessitates a review of previous seismic designs and theories. This paper investigates the characteristics and rules of the seismic damage of large span spatial structure during the Lushan earthquake and discusses the possible causes of such damage. A shaking table test was conducted with a down-scaled model of a double-layer cylindrical shell structure to obtain the dynamic response of a structure by reasonably arranging the acceleration, velocity and displacement measuring points. The failure pattern and progressive collapse process of the structure under a severe earthquake were investigated. The buckling of members increased with the increment of ground motion, although this effect was not considered in the present code for seismic design for double-layer shell spatial structures. The seismic damage in the test was mainly represented by overall buckling of the upper chord, web member and lower chord, which is the direct reason for the structural collapse during a severe earthquake. The test results indicated that the change in surface curvature of the structure resulting from deformation during a severe earthquake transformed gravitational potential energy into kinetic energy and caused chord members to impact and fracture, thereby inducing progressive collapse of the structure. The findings of this paper provide a basis for the seismic theory and design of large span spatial steel structures. The buckling effect of double-layer cylindrical shell structures, the dynamic amplification effect of the support structures, and the transformation of gravitational potential energy to kinetic energy in particular would be of interest to researchers and designers.

Introduction

As one of the major forms of large-span spatial structures, spatial double-layer cylindrical shell structures have developed rapidly over the last four decades and applied widely in large-scale public facilities. Their progressive collapse can cause heavy economic losses and casualties and have a huge impact on national security and social stability. The progressive collapse of such structures is caused by local failure under accidental loads or unexpected loads. Such a failure can cause the failure of adjacent members or nodes, which leads to chain reaction until the structure collapses or causes much greater failure than the initial damage [1]. Most current researches on collapse are focused on frame structures and high-rise buildings. Starossek [2] classifies collapse into four types including collapse caused by load redistribution, collapse caused by explosion or impact, collapse caused by instability and collapse caused by multiple effects. Mlakar et al. [3] note that when the stiffness of beam column joint of the frame structure equals the beam shear stiffness, the failure of one column will cause an incremental collapse. Kim et al. [4] suggest that a catenary mechanism represents the anti-collapse effect of frame beam after the failure of a structural column, which is the last stage of anti-progressive collapse of the frame structure. He et al. [5] adopt a response spectrum method to study the dynamic performance of structures under earthquake loads, and Ye et al. [6] investigated and analysed the seismic responses of structures under multi-excitation in detail and compared the results to those of uniform excitation. Yu et al. [7] applied a structural equivalent damping ratio to study the collapse mechanism of a shell structure under a severe earthquake and investigated the importance of integrated structural analysis. Dusenberry et al. [8] and Lee et al. [9] propose the elastic–plastic evaluation method that takes the catenary energy dissipation into consideration to investigate the structural non-linear properties. The failure mechanism of single layer reticulated dome and cylindrical shell under strong earthquake was investigated considering material damage accumulation by zhou et al. [10], [11]. Izzuddin et al. [12] propose a computational energy method using a substructure method that could decrease computational costs. Agarwal et al. [13] present that small breakage sources in structures may cause large-scale damage based on the graph theory method, although this method is actually a structural stiffness judgement method. The lognormal distribution was selected by Zhang et al. [14] to appraise collapse loads to gain the dynamic collapse fragility curves for single-layer reticulated domes. The implicit and explicit methods were used to evaluate the progressive collapse resistance of double–Layer grid space structures by Fu et al. [15]. Based on the definition of progressive collapse, the underlying mechanism mainly involves the following three aspects: accidental load action; local damage and transmission; and global collapse or disproportionate structural damage. Because of the uncertainty of accidental loads, the effective structural resistance to collapse under such loads is difficult to ensure under conventional design parameters; thus, commensurable design norms and codes have been published in the U.K., Europe, the U.S., Japan, and China [16], [17], [18], [19], [20], [21]. Although the above-mentioned standards give the provisions that progressive collapse should be avoided, there is no quantitative design method and no specific implementation means. The concept design and concrete method of resisting progressive collapse are put forward, but the regulation is too vague and simple. In addition, the theoretical research, numerical simulation, experimental research and corresponding specifications of progressive collapse and anti collapse are still limited to frame structures and multi-storey, and the relevant research results also reflect the progress in this field, while the anti collapse research of large-span spatial structures represented by cylindrical shells is rarely carried out. However, many cases of such structural damage have occurred in earthquakes in recent years. Based on this background, this paper carries out the progressive collapse test of cylindrical shell, and obtains its collapse resistance performance, which provides support for theoretical research and engineering practice for cylindrical shell.

Experimental study represents a reliable research method because it can be the most direct way to investigate and measure the mechanical properties and responses of the structure. Sasani et al. [22] conducted progressive collapse tests of two constructed steel concrete structures and obtained the time history changes of the structure under an explosion load as a trigger action. Yi et al. [23] indicates that the catenary mechanism and frame mechanism of the structure resist collapse under sudden accidental dynamic loads through a progressive collapse test of a steel concrete structure. Suita et al [24] studied the progressive collapse safety redundancy of the structure under earthquake loads based on four groups of full-size steel-frame tests using Japan E-Defence shaking table. In recent years, scholars have started to focus on the progressive collapse and anti-collapse performance of spatial lattice structures. Nie et al. [25], [26], [27], [28], [29] investigated the seismic mechanism and failure pattern of a spatial structure under cyclic loads and earthquake loads via systematic structure pseudo-static tests and shaking table tests. However, the progressive collapse incidents of spatial shell structures that have occurred in recent years indicate that further study is warranted in this research area.

In this study, large-span spatial double-layer cylindrical shell that experienced seismic damage during the Lushan earthquake was systematically summarized and analyzed. To investigate and research the seismic performance and progressive collapse law of spatial double-layer cylindrical shells, a shaking table test was performed on a reduced scale model and two typical earthquake ground motion records were used in different input principal directions. Based on the arrangement of the acceleration, speed and displacement measuring points in different locations of the structure, the structural dynamic responses under different ground motions were obtained. The seismic failure pattern and the whole progressive collapse process of the structure were investigated, and the causes of structural damage are summarized and discussed. Moreover, reasonable suggestions for the theoretical research and design of such structures are provided.

Section snippets

Seismic damage of spatial Double-layer cylindrical shell

The incidence of progressive collapse of spatial shell structure under different loads is quite common, and more than 50 progressive collapse incidents of such structures have been documented. The safety of spatial lattice structures was first holistically and systematically tested during the Lushan earthquake of 2013 in China. Circular latticed shell and double-layer flat grid suffered different degrees of damage such as the Lushan gymnasium and Lushan high-school gymnasium [30]. The

Outline of the test

Double-layer shell structures suffered seismic damage during the Lushan earthquake because of amplification of the coupling effect between the lower supporting structure and the upper shell structure. Such a coupling effect includes the acceleration amplification effect and the uneven distribution of stiffness of the lower supporting structure. A significant eccentric effect was found in the lower supporting frame structure of the Baoxing gymnasium. A new shaking table model composed of a lower

Test phenomenon of severe damage

From a general view, with incremental inputs of ground motion, the vibration amplitude of the upper shell structure increases. The structure was under elastic status and plastic deformation was not observed before the input excitation of Taft-X with peak value of 0.3 g. When this motion was inputted, obvious seismic damage occurred in the structure, which was represented as the global buckling of the upper, web, and lower chords and was close to the actual seismic phenomenon. The global state

Conclusions

The purpose of this investigation was to study and examine the dynamic behaviour of double-layer shell spatial structures under earthquake ground motion. Based on the seismic damage investigation at the Lushan earthquake and the test results, the following conclusions can be made.

The seismic damage investigation of the Baoxing gymnasium stand indicates that the acceleration amplification effect of the lower supporting column and the torsion effect caused by the uneven stiffness distribution of

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This research work was jointly funded by Scientific Research Fund of Institute of Engineering Mechanics, China Earthquake Administration (2018B06; 2019EEEVL0201) and National Natural Science Foundation of China (51678544).

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